This invention relates to optical connector adapters for use in optical fiber transmission and, more particularly, to an adapter for creating an electrical indication of the condition of the connector and for locking the connection during signal transmission.
Optical fiber transmission systems are becoming widely used in the transmission of signals such as data, voice, and the like, and in many instances, are replacing traditional electrical systems. Many of the arrangements common to electrical systems, such as coupling, interconnection, splicing, and the like have their counterparts in optical systems but, because of the totally different characteristics of the transmission media, i.e., optical fiber versus metallic wire, connectorization, splicing, and the like involve quite a different apparatus. Where, for example, it is necessary to make a great number of connections in one location, both systems may use what is referred to in the art as patch panels, which provide arrays of connector adapters for interconnection, but the interconnections themselves are generally quite different.
It is common practice in the optical connector art to terminate a length of optical fiber with a connector, an example of which is the SC type connector that is shown and described in U.S. Pat. No. 5,212,752 of Stephenson et al. There are numerous types of such fiber terminating connectors, and, inasmuch as there has been little effort directed to standardization, each type of connector generally requires a different coupling arrangement to permit interconnection of two fibers, for example.
When large numbers of such interconnections are to be made, it is common practice to use patch panels for holding an array of a large number of coupler adapters. Thus, there literally can be hundreds of such adapters, all in close proximity to each other, mounted in the panel. As long as only a single type of connector, such as the SC connector, is involved, simple adapters may be used for plugging in the connectors from each side of the patch panel. In view of the fact that there are several different types of connectors in widespread use today, it has become common practice to replace the simple adapters with buildout blocks or buildout coupling adapters. In U.S. Pat. No. 5,274,729 of King et al., there is shown a buildout coupling adapter system in a patch panel that makes possible interconnections among the several different types of connectors in any combination thereof. As can be seen in that patent, a buildout block at one side (or end) thereof is configured the same as a simple coupler adapter having a keyway for receiving, for example, an SC connector. The other end of the buildout block is formed to receive a buildout which may be configured to receive and hold, for example, an SC, an ST, an LC, or an FCMV connector. Thus, the patch panel may be, on the one side thereof, pre-connectorized with optical fibers all of which are terminated by, for example, SC connectors, and the other side of the panel is ready to receive pre-connectorized fibers terminated by any one of the numerous connectors. Such an arrangement is more versatile and adaptable than those arrangements which are limited to a single type of pre-connectorized fiber. Such an arrangement also functions well in those installations where one side of the panel is not readily accessible. Thus, before being mounted in position, the panel can be pre-connectorized on the side which will be relatively inaccessible, after which it can be mounted in place, ready to receive the numerous connections thereto, regardless of connector type. In order to pre-connectorize the panel, the adapters are usually made of two parts, a base member (buildout block) that attaches to the panel and a cap member (buildout) which receives the connector plug, and which is insertable into the base member. Such a two part adapter is commonly referred to as a split adapter. One particular advantage of a split adapter, in addition to the build-out feature, is that access to the ferrule distal or butting ends for cleaning (or repair) obtains when the cap and base are separated.
In any such arrangement there is a potential safety hazard that is often present. Where one or more of the pre-connectorized fibers is carrying optical energy, such energy can be emitted from the end of the fiber connector and pass through the unoccupied buildout block or coupling adapter to the side of the panel where connections are to be made. This optical energy can be harmful for the operator or installer and can be especially harmful to his or her eyes. This hazard is most prevalent when an active connection has to be repaired, cleaned or otherwise altered by removal of an existing connectorized fiber and replacement with another. In such an instance, it might be difficult or otherwise impractical to shut off the signal transmission in that particular fiber circuit, hence, the installer is forced to deal with a light emitting junction or connection.
This hazard has long been recognized and there are numerous arrangements in the prior art for blocking any light emanating from a fiber connection through an open adapter. In U.S. Pat. No. 5,678,268 of Stephenson et al., there is shown a pivotable optical shutter arrangement wherein a normally closed pivotable shutter blocks the open exit of an adapter when a connector plug is removed. The shutter advantageously requires only one motion to open it to permit insertion of a plug or connector into the adapter. Such a shutter as shown in the patent is operable by only one hand instead of prior art arrangements which generally require awkward use of two hands by the installer. One of the disadvantages of any shutter arrangement however, is that they are easily xe2x80x9cdefeatablexe2x80x9d in that they can be, during installation of large numbers of connectors and in the interest of expedition, for example, temporarily fixed in the open position, thus contravening their purpose. In addition, the fiber optical transmission art has progressed to the use of higher and higher light energy or power, and has reached a point where shutter arrangements in general have, because of the large light energy, become transparent to much of the energy in the form of infra-red light, which is commonly used. Additionally, when the light intensity is very high, actual damage to the optical connector and the associated fibers can occur.
There are many arrangements in the prior art aimed primarily at reducing the possibility of injuring the operator, such as are shown in U.S. patent application Ser. No. 09/748,906, filed Dec. 27, 2000 of Norman R. Lampert et al. and Ser. No. 09/784,574, filed Feb. 15, 2001 of Norman. R. Lampert et al. In the Lampert et al. arrangement, insertion of the connector plug into the adapter creates a signal, such as by activating a switch, which generates an indication that the connection is completed and signals may be transmitted through the connection. Withdrawal of the connector plug from the adapter deactivates the switch or other signal generator, indicating that the adapter is not to be used in transmitting optical signals.
With the increasing use of high power signal transmission, it is important that the butting ends of the connector ferrules within the adapter not be separated while high power light is being transmitted therethrough. Such a separation can, in the high power use, cause severe damage to the distal (or butting) ends of the ferrules. This is especially important with split adapters in a build out arrangement, inasmuch as different types of connector plugs may be used, hence generation of a signal for signaling that the signal transmission should be turned off or on should not depend upon especially designed or otherwise modified plugs. Thus any safety arrangement should, preferably, be contained within the split adapter. Further in the interests of safety, it is preferable that an operator or installer should have to take positive action to prepare the connection for signal transmission, or to disconnect the connection. In the prior art, such as in the aforementioned Lampert et al. arrangements, the operation does not require the operator or installer to take any positive action other than inserting the connector plug into the adapter or withdrawing it therefrom. It is, therefore, desirable that the operator be able to cut off the transmission through the connector prior to separation of the butting ends of the connector plug ferrules, and to delay optical transmission until the plug is fully inserted in the adapter.
The invention as disclosed herein is directed primarily to its application in a split adapter. However, the principles of the invention are readily adaptable for use in a unitary adapter.
The present invention, in a first embodiment thereof, is a split adapter comprising a base member for mounting to a panel, for example, and a cap member insertable therein. The cap member has first and second side latching members and a top latching arm which mate with corresponding latch receivers in the base to lock the cap in place in the base. The cap maybe removed from the base by depressing the latching arm and exerting a pulling force (such as one-half to one pound) on the cap to disengage the side latches. The side latches have enlarged portions at this distal ends, which are angled, as will be disclosed hereinafter, to function as latches but which are defeatable by the pulling force. As will be more clearly apparent hereinafter, when a connector plug is inserted into the cap, it serves to hold the side latches in place so that the cap is firmly attached to the base and separation effectively prevented.
In accordance with the invention, the base member has a switch mounted therein and the cap member has a switch actuation lever slidably mounted therein. Many forms of actuation lever can be substituted, such as a rotatable or pivoted actuation lever. The lever has a flexible portion which permits it to be moved out of the way for insertion of the connector plug into the cap. After the plug is inserted, the lever is slid forward by the installer or operator to where it actuates the switch, which is preferably of the plunger type, and, at the same time latches into place in the forward position. In this position, a projection on the lever bears against the underside of the top latching arm, preventing its being depressed, thereby further insuring that the cap and base are firmly locked together. The lever has an enlarged end portion which overlies and masks the latching arms of the connector plug, thereby preventing removal of the plug when the lever is in the forward position. Furthermore, in the forward or switch actuating position of the lever, the enlarged end, which masks the latching arm of the connector plug, cannot be bent out of the way, thereby insuring that the connector plug cannot be disconnected. The net result is that the cap is affixed to the base and the plug is affixed to the cap, thereby insuring against accidental or unintentional separation of the components. The actuated switch can close an electrical circuit which, for example, may directly halt signal transmission through the connector, or which may generate a signal informing an operator or monitor to halt the signal transmission. It is, of course, preferable that the circuit cut off transmission, such as by turning of the power laser, without human intervention.
When a disconnect is desired, the actuation lever must be pulled back to provide access to the plug latching arm, thereby halting the signal transmission by opening the switch. It is only after this first step that the enlarged end portion may be bent out of its masking position to give the operator or installer access to the connector plug for removal thereof.
It can be seen, and further will be more readily apparent, that when a connector plug is not in the cap, there is no signal transmission. Further, in order for signal transmission to commence, the operator must first insert the connector plug and then slide the actuation lever forward to its latched position wherein the switch is actuated to permit signal transmission and the connection cannot be broken, as by separation of the parts, thereby insuring protection of the ferrules and of any personnel in the vicinity.
In a second embodiment of the invention, the top latching arm on the cap may be eliminated in the interest of creating a smaller footprint, and the side latches relied upon to hold the cap and base together.
While the principles of the invention are shown and described as embodied in a split adapter comprising a base and a cap, the adapter may be a unitary housing in which the operative feature and components of the invention are included.
These and other features of the present invention will be more readily apparent from the following detailed description, read in conjunction with the following drawings.